565 research outputs found
Near-Limb Zeeman and Hanle Diagnostics
"Weak" magnetic-field diagnostics in faint objects near the bright solar disk
are discussed in terms of the level of non-object signatures, in particular, of
the stray light in telescopes. Calculated dependencies of the stray light
caused by diffraction at the 0.5-, 1.6-, and 4-meter entrance aperture are
presented. The requirements for micro-roughness of refractive and reflective
primary optics are compared. Several methods for reducing the stray light (the
Lyot coronagraphic technique, multiple stages of apodizing in the focal and
exit pupil planes, apodizing in the entrance aperture plane with a special
mask), and reducing the random and systematic errors are noted. An acceptable
level of stray light in telescopes is estimated for the V-profile recording
with a signal-to-noise ratio greater than three. Prospects for the limb
chromosphere magnetic measurements are indicated.Comment: 11 pages, 3 figure
The Politics of Pleasure: Promenading on the Corniche and Beachgoing
Can the pleasures of young Palestinian women from refugee camps in promenading on the Beirut seaside Corniche on a warm summer evening be political? Or days spent at women-only beaches? If so, how do we understand such pleasure as everyday practices, as a politics of the present moment, or conversely (or simultaneously) as mechanisms of being co-opted into a broader apparatus of consumerist ideology and capitalist complacency? Drawing on ethnographic research over 2 years I argue that these moments of pleasure are caesuras in the massive apparatus of power – welded from strands of work, neoliberal practice, nationalist certitudes and political exclusion – which binds these women. These acts of pleasure cannot easily be categorised as ‘resistance’ but I argue that they should not facilely be considered reinforcements of hegemonic control either. They are momentary and ephemeral recognitions of ordinary life lived in hard times, attempts at clawing back an instant of joy from the drudgery of the everyday, and a surrender to the enjoyment of conviviality in public and urban spaces. If they are at all political, they are so because such conviviality is ever harder to sustain in the calamity of hopelessness that characterises so much politics today
Lines Missing Every Random Point
We prove that there is, in every direction in Euclidean space, a line that
misses every computably random point. We also prove that there exist, in every
direction in Euclidean space, arbitrarily long line segments missing every
double exponential time random point.Comment: Added a section: "Betting in Doubly Exponential Time.
Detection of a low-grade enteroviral infection in the islets of Langerhans of living patients newly diagnosed with type 1 diabetes
Journal ArticleThis is an author-created, uncopyedited electronic version of an article accepted for publication in Diabetes. The American Diabetes Association (ADA), publisher of Diabetes, is not responsible for any errors or omissions in this version of the manuscript or any version derived from it by third parties. The definitive publisher-authenticated version is available in Diabetes, May 2015, vol. 64, no. 5 pp. 1682-1687 in print and online at http://diabetes.diabetesjournals.org/content/64/5/1682.abstractThe Diabetes Virus Detection study (DiViD) is the first to examine fresh pancreatic tissue at the diagnosis of type 1 diabetes for the presence of viruses. Minimal pancreatic tail resection was performed 3-9 weeks after onset of type 1 diabetes in six adult patients (age 24-35 years). The presence of enteroviral capsid protein 1 (VP1) and the expression of class I HLA were investigated by immunohistochemistry. Enterovirus RNA was analyzed from isolated pancreatic islets and from fresh-frozen whole pancreatic tissue using PCR and sequencing. Nondiabetic organ donors served as controls. VP1 was detected in the islets of all type 1 diabetic patients (two of nine controls). Hyperexpression of class I HLA molecules was found in the islets of all patients (one of nine controls). Enterovirus-specific RNA sequences were detected in four of six patients (zero of six controls). The results were confirmed in various laboratories. Only 1.7% of the islets contained VP1(+) cells, and the amount of enterovirus RNA was low. The results provide evidence for the presence of enterovirus in pancreatic islets of type 1 diabetic patients, which is consistent with the possibility that a low-grade enteroviral infection in the pancreatic islets contributes to disease progression in humans.Academy of FinlandSouth-Eastern Norway Regional HealthAuthorityNovo Nordisk FoundationPEVNET (Persistent Virus Infection in Diabetes Network) Study GroupEuropean Union’s Seventh Framework ProgrammeSwedish Medical Research CouncilDiabetes Wellness FoundationJDR
Effect of Intraduodenal Bile and Na-Taurodeoxycholate on Exocrine Pancreatic Secretion and on Plasma Levels of Secretin, Pancreatic Polypeptide, and Gastrin in Man
The effect of intraduodenally administered cattle bile (CB) and Na-taurodeoxycholate (TDC) on basal pancreatic secretion and plasma levels of secretin, pancreatic polypeptide (PP), and gastrin were investigated on two separate days in 10 fasting volunteers. Doses of 2-6 g CB and 20&600 mg TDC were given intraduodenally at 65-min intervals. Volume, bicarbonate, lipase, trypsin, amylase, and bilirubin were measured in 10-min fractions of duodenal juice, and GI peptides determined by radioimmunoassay. CB and TDC enhanced significantly and dose-dependently volume, bicarbonate and enzyme secretion, and plasma secretin and PP levels. In contrast, plasma gastrin showed only a marginal increase. We conclude that the hydrokinetic effect of intraduodenal CB and TDC is at least partially mediated by secretin. Gastrin could be ruled out as a mediator of the ecbolic effect, whereas other GI peptides, primarily CCK, and/or neural mechanisms must be considered possible mediators. Both pathways may also play a role in the PP release
Matrix-free calcium in isolated chromaffin vesicles
Isolated secretory vesicles from bovine adrenal medulla contain 80 nmol of Ca2+ and 25 nmol
of Mg2+ per milligram of protein. As determined with a Ca2+-selective electrode, a further accumulation
of about 160 nmol of Ca2+/mg of protein can be attained upon addition of the Ca2+ ionophore A23187.
During this process protons are released from the vesicles, in exchange for Ca2+ ions, as indicated by the
decrease of the pH in the incubation medium or the release of 9-aminoacridine previously taken up by the
vesicles. Intravesicular Mg2+ is not released from the vesicles by A23 187, as determined by atomic emission
spectroscopy. In the presence of N H Q , which causes the collapse of the secretory vesicle transmembrane
proton gradient (ApH), Ca2+ uptake decreases. Under these conditions A23 187-mediated influx of Ca2+
and efflux of H+ cease at Ca2+ concentrations of about 4 pM. Below this concentration Ca2+ is even released
from the vesicles. At the Ca2+ concentration at which no net flux of ions occurs the intravesicular matrix
free Ca2+ equals the extravesicular free Ca2+. In the absence of NH4C1 we determined an intravesicular
pH of 6.2. Under these conditions the Ca2+ influx ceases around 0.15 pM. From this value and the known
pH across the vesicular membrane an intravesicular matrix free Ca2+ concentration of about 24 pM was
calculated. This is within the same order of magnitude as the concentration of free Ca2+ in the vesicles
determined in the presence of NH4C1. Calculation of the total Ca2+ present in the secretory vesicles gives
an apparent intravesicular Ca2+ concentration of 40 mM, which is a factor of lo4 higher than the free
intravesicular concentration of Ca2+. It can be concluded, therefore, that the concentration gradient of free
Ca2+ across the secretory vesicle membrane in the intact chromaffin cells is probably small, which implies
that less energy is required to accumulate and maintain Ca2+ within the vesicles than was previously
anticipated
Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data
The Mw 7.7 2007 November 14 earthquake had an epicentre located close to the city of Tocopilla, at the southern end of a known seismic gap in North Chile. Through modelling of Global Positioning System (GPS) and radar interferometry (InSAR) data, we show that this event ruptured the deeper part of the seismogenic interface (30–50 km) and did not reach the surface. The earthquake initiated at the hypocentre and was arrested ~150 km south, beneath the Mejillones Peninsula, an area already identified as an important structural barrier between two segments of the Peru–Chile subduction zone. Our preferred models for the Tocopilla main shock show slip concentrated in two main asperities, consistent with previous inversions of seismological data. Slip appears to have propagated towards relatively shallow depths at its southern extremity, under the Mejillones Peninsula. Our analysis of post-seismic deformation suggests that small but still significant post-seismic slip occurred within the first 10 d after the main shock, and that it was mostly concentrated at the southern end of the rupture. The post-seismic deformation occurring in this period represents ~12–19 per cent of the coseismic deformation, of which ~30–55 per cent has been released aseismically. Post-seismic slip appears to concentrate within regions that exhibit low coseismic slip, suggesting that the afterslip distribution during the first month of the post-seismic interval complements the coseismic slip. The 2007 Tocopilla earthquake released only ~2.5 per cent of the moment deficit accumulated on the interface during the past 130 yr and may be regarded as a possible precursor of a larger subduction earthquake rupturing partially or completely the 500-km-long North Chile seismic gap
The Role of Bile in the Regulation of Exocrine Pancreatic Secretion
As early as 1926 Mellanby (1) was able to show that introduction of bile into the duodenum of anesthetized cats produces a copious flow of pancreatic juice. In conscious dogs, Ivy & Lueth (2) reported, bile is only a weak stimulant of pancreatic secretion. Diversion of bile from the duodenum, however, did not influence pancreatic volume secretion stimulated by a meal (3,4). Moreover, Thomas & Crider (5) observed that bile not only failed to stimulate the secretion of pancreatic juice but also abolished the pancreatic response to intraduodenally administered peptone or soap
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